MIG type magnetic heads are known which include first and second cores of ferrite and a soft magnetic thin film of Sendust or the like on the gap-facing surface of at least one of the cores, the thin film having a higher saturation magnetic flux density Bs than the cores. These magnetic heads are effective for recording information in magnetic recording media having a high coercive force because an intense magnetic flux can be applied from the soft magnetic thin film to the media.
Also, flying type thin film magnetic heads now find commercial application by virtue of their excellent capabilities of high density recording and high speed data transfer.
Further, thin film magnetic heads use soft magnetic thin films of Permalloy, Sendust and similar materials having a high saturation magnetic flux density Bs as upper and lower magnetic pole layers for generating a high density magnetic flux.
It should be noted that these soft magnetic thin films used in magnetic heads have a saturation magnetic flux density Bs of at most about 12,000 G. Therefore, conventional magnetic heads have insufficient overwrite and other electromagnetic properties while a higher saturation magnetic flux density Bs is required for magnetic recording media having a high coercive force.
Further, Fe base soft magnetic thin films having enhanced (100) orientation are known to exhibit excellent soft magnetic properties due to low crystallographic magnetic anisotropy. However, conventional gas phase methods such as sputtering fail to form Fe base soft magnetic thin films having enhanced (100) orientation, but rather result in thin films having orientation in (110) plane or no orientation. The fabrication of thin films having enhanced (100) orientation requires the use of substrates of special materials such as ZnSe or monocrystalline substrates of GaAs or the like which have (100) orientation or an enhanced degree of (100) orientation.
Since thin films having enhanced (100) orientation can be formed only under limited conditions, it is very difficult for magnetic heads to have soft magnetic thin films which have (100) orientation or an enhanced degree of (100) orientation.
In turn, Fe-N soft magnetic thin films having a higher saturation magnetic flux density Bs than Sendust can be formed by sputtering an Fe target in a Gas mixture of Ar and N.sub.2. This is because inclusion of N helps form finer crystal Grains of Fe and reduce magnetic anisotropy dispersion.
For example, Japanese Patent Application Kokai No. 15907/1989 discloses a soft magnetic thin film based on Fe and containing iron nitride in the form of Fe.sub.4 N and/or Fe.sub.3 N. This soft magnetic thin film has magnetic properties suitable as magnetic heads as typified by a saturation magnetic flux density of 15,000 G or higher and a low coercive force Hc.
The Fe-N soft magnetic thin films, however, are less heat resistant so that they experience a rapid rise of coercive force Hc at a temperature of the order of 350.degree. C. since their grain size increases at such temperatures.
These soft magnetic thin films are thus difficult to apply to magnetic heads of the MIG and EDG types in which temperatures of about 450.degree. to 700.degree. C. are encountered during glass welding and other heat treatment as well as thin film magnetic heads in which temperatures of about 350.degree. C. or higher are encountered during film formation as by sputtering. In addition, they cannot be enhanced in (100) orientation simply by forming films on conventional substrates by sputtering and other gas phase methods.